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(No Model.) 4 SheetsSheet 1.

J. THORNE & E. B. BURR.

ELECTRICAL HEAD LIGHT.

No. 436,677. Patented Sept. 16, 1890.

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(No Model.)

4 Sheets-Sheet 2. J. THORNE & E. B. BURR.

ELECTRICAL HEAD LIGHT.

No. 436,677. Patented Sept. 16, 1890.

M M j THE NDRmS PETERS co., wum-umu, wasumcn'on, o. c.

(No Model.) I 4 Sheets-Sheet 3. J. THORNE & E. B. BURR.

ELECTRICAL HEAD LIGHT.

No. 436,677. Patented Sept. 16, 1890..

(No Model.) 4 Sheets-Sheet 4. J. THORNE & E. B .BURR.

ELECTRICAL HEAD LIGHT.

No. 436,677. Patented Sept. 16, 1890.

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UNITED STATES PATENT OFFICE.

JAMES Tl-IORNE AND EBENEZER BANTON BURR, OF LONDON, ENGLAND;

SAID BURR ASSIGNOR TO SAID THORNE.

ELECTRICAL HEAD-LIGHT.

SPECIFICATION forming part of Letters Patent No. 436,677, datedSeptember 16, 1890.

Application filed July 2, 1888. Serial No. 278,744.. (No model.)Patented in England February 12, 1887, No. 2,262, and May 13, 1887, No.7,046; in Belgium April 30, 1888, No. 81,377, and in France June8,1888,No.189,824.

invented new and useful Improvements in Signal and other Lamps, (forwhich we have obtained patents in Great Britain, No. 2,262,

' dated February 12, 1887, and No. 7,0i6, dated May 13,1887; in France,No. 189,824, dated June 8, 1888, and in Belgium, No. 81,377, dated April30, 1888,) of which the following is a specification, reference beinghad to the accompanying drawings.

The main object of the present invention is to provide an electrichead-lamp, taillamp, side-lamp, or other signal-lamp for railwaypurposes, which will be complete in itself, having no external wires orconnections. The present improvements are, however, applicable tomast-head lamps or other signallamps for ships, to lamps for omnibuses,tramway-cars, cabs, velocipedes, or other vehicles, and also to lampsfor telegraphing by means of flashing-signals and for mining or otherpurposes.

In our improved lamp we employ a lens, of which the interior surface isplane and the exterior surface is so curved in one sweep as to give aparallel or nearly parallel beam from a point. The curvature of theexterior surface of the lens should for this purpose be parabolic orapproximately parabolic, or elliptic or approximately elliptic. \Vesometimes em ploy a reflector of corresponding form and so arrange thesaid lens and reflector relatively to each other and to the light thattheir foci correspond with each other or lie in the axial line common toboth lens and reflector, and the rays of light concentrated by thereflector will pass through the lens. By reason of the peculiarformation and arrangement of the lens and reflector we are enabled toplace the light and reflector nearer the lens than heretofore, and thuseconomize space in the lamp. Moreover, in a lamp provided with ourimproved lens and reflector, instead of the shape of the lighter flameof the lamp being visible through the lens, as in lamps heretoforeconstructed, the lens presents the appearance of an illumined disk, thelight having substantially the same brilliancy over the entire area ofthe lens, and the lamp throws out a beam of intense light, which can beseen at: a great distance from the lamp. Vi e thus obtain much betterresults than heretofore with respect to the intensity of the beamprojected from the lamp.

We combine with alantern or lamp-casing in the manner herein describedan electric incandescent lamp, an electric battery or accumulator, and alens of the kind herein mentioned, with or without a reflector, allarranged in the said lantern or casing, so that the apparatus can bereadily inserted in or removed from its place on a vehicle or other objeet without the necessity for connecting or disconnecting any wires.Moreover, as there is no need for ventilation, the said lanternorlampcasing can be made without a chimney or ventilator and can beclosed (hermetically, if desired) so as to exclude dust. We arrange thesaid reflector and lens relatively to each other in the manner abovedescribedthat is to say, so that their foci correspond with each other,being situated in the axial line common to both lens and reflector. Bythis arrangement of the lens and reflector we are enabled to place thelight and the reflector much nearer the lens than heretofore, and thusleave space within the lantern or casing .forthe electric batterywithout the necessity for increasing the size of the lantern or casingas compared with those ordinarily used for similar purposes. Moreover,we obtain very good results in respect of the intensity of the lightpassed through the lens.

In the accompanying drawings, Figure 1 is a vertical longitudinalcentral section ofone form of our improved apparatus. Fig. 2is atransverse section on thelineacx, Fig. 1. Fig. 3 is a verticaltransverse central section of another form or modification of our saidapparatus; and Fig. 4 is a vertical longitudinal sect-ion on the line 00ac, Fig. 3.

Like letters indicate corresponding parts throughout the drawings.

a is the lantern or lamp-casing.

bis the 1ens,which is secured therein in any well-known or suitablemanner.

c isa parabolic reflector,which is made with a socket 0', adapted to fitupon a bracket d, formed on or attached to a sliding plate (I.

e is the battery, which is placed upon and, if necessary, attached tothe said sliding plate.

fis an electric incandescent lamp of any suitable description, which issuspended from wires passed through a block or piece of insulatingmaterial inserted in a tube or socket c fixed in the reflector c, thesaid block or piece being secured by means of a set-screw 0 The plate clis fitted between guides a, formed on or attached to the casing a, sothat the said plate, with thebattery, the lamp, and the reflector, canbe very readily inserted in and removed from the said casing.

To provide for tightly closing the battery and at the same time firmlysecuring it in the casing and preventing its withdrawal except by anauthorized person, we employ a screw g, which is passed through a tappedhole in a socket g, secured to the casing a. The lower end of this screwbears against the lid 8 of the battery and holds the same down, so thatthe battery is kept tightly closed, a sheet or washer of india-rubber orother elastic material being preferably placed between the lid and bodyof the said battery to insure tightness of the joint. The upper end ofthe screw g is made square or of other suitable shape, so that a keymaybe fitted thereon to permit the turning of the said screw in eitherdirection. The said key is so made that it will fit into the hole orcavity g in the socket g,

' which hole or cavity may be of any desired shape.

WVhen a primary battery is employed, we

- prefer to use that described in the specification of former LettersPatent of Great Britain, dated September 2, A. D. 1882, No. 4,198. NVemay, however, use any other suitable primary battery, or we may use asecondary battery or accumulator.

h is a switch. for completing or interrupting the electric circuit forthe purpose of putting the apparatus into or out of action when desired.

We sometimes arrange in combination with this switch a clock-work devicefor in dicating the length of time during which the lamp has beenalight, so that the state of the battery may be readily ascertained atany time. This device is so connected with the switch that when thelight is turned off the movement of the clock-work will be arrested; orwe use an indicator which may be adjusted by hand for the purpose abovespecified.

Instead of making the lens of the ordinary spherical form, we prefer tomake it in the form of a paraboloid-for example, as shown in thedrawings. WVe sometimes, however, make it elliptic or approximatelyelliptic. Whatever may be the shape of the reflector and lens used, itis advantageous to so adjust the reflector relatively to the lens thattheir foci will correspond or lie in a common axial line, as abovedescribed.

In some instances we dispense with the reflector shown in Figs. 1 and 2and provide a tube, which is inserted and secured in the aperture in thefront of the lantern or lamp-casin g, and in the outer end of which aparabolic lens is fixed. This tube is sometimes made to serve as areflector, in which case we prefer to make it in the form of a truncatedcone or of a truncated paraboloid.

The lamp or apparatus shown in Figs. 1 and 2 will serve very efficientlyas a head-lamp or tail-lamp for use on a railway-carriage or locomotive.

Thelamp shown in Figs. 3 and 4 is designed as aside-lamp forarailway-carriage. It has two parabolic lenses 1) and a double reflectorthat is to say, two parabolic reflectors c, portions of which are cutoff through a plane perpendicular to their axes and which are united atc the electric incandescent lamp f being placed in the center, as shown.

When used for railway purposes, our improved lamp aflords, among others,the following advantages,viz: There are no external wires orconnections. Thereforethe lampcan be readily transferred from onevehicle to another, and no disconnection of wires is necessary whenslipping a carriage. There is no need of ventilation. Therefore thecasing can be made without a chimney or ventilator, and can be tightlyclosed so as to exclude dust. No trimming is required, as in oil-lamps,and there is no smoke, grease, or soot to dim the lens and obscure thelight. The light cannot be effected or extinguished, as in oil-lamps, byair currents or eddies produced by the motion of the train or otherwise.There-is no risk of fire in case of breakage of the lamp in a collisionor other accident. The lamp can be easily handled, and the battery canbe very readily withdrawn, recharged, and replaced.

\Ve sometimes provide interchangeable slides of greenorothercoloredglass-as shown, for example, at z in Fig. lwhich can bevery readily inserted in and withdrawn from the lantern or lamp-casingfor the purpose of changing or determining the color of the light.

For railway purposes our lamp has the further advantage that theseslides can be changed without liability to extinctionof the light whenthe door of the casing is opened. The necessity for any mechanicaldevices for changing them without opening the said casing is thusobviated.

We do not confine ourselves, save in respect of lens and reflector, toany special form or construction of the parts of our improved lamp, asthese will depend to a great extent upon the purpose for which the lampis required, and can be considerably modified Without departing from thenature of our said invention.

It is evident that our improved apparatus may be adapted fortelegraphingby means of reflector being in the same axial line, and anelectric lamp, a battery, and connections, all inclosed in the casing,substantially as shown and described.

2. The herein-described lamp or lantern, consisting of the closed casinga, the lens I), having a plane interior surface and anapproximatelyparabolic external surface, the parabolic reflector 0,having its focus in the same axial line with the focus of thelens, thebattery 6, incandescent lamp f, and batteryconnections, all inclosed inthe casing a, and the switch h on the outside of said casing,substantially as shown and described.

In testimony whereof we have hereunto set our hands and aflixed ourseals this 18th day 0 of June, 1888.

JAMES THORNE. [n 5.] EBENEZER BAN'lON BURR. in s] Witnesses:

RoBT. JNo. DANTER, W. J. HAMMOND.

